Catalytic converter-muffler

ABSTRACT

A catalytic converter-muffler device having a V-shaped bed configuration providing optimum gas flow characteristics and minimization of differential expansion problems from hightemperature conditions. A preferred unit has an oval outer chamber, a catalyst reservoir section, and curved sidewalls for the internal catalyst retaining screens so as to preclude buckling which occurs with flat plate members.

United States Patent De Palma et a1.

[ 1 Mar. 14, 1972 CATALYTIC CONVERTER-MUFFLER Inventors: Ted V. DePalma, Roselle; Martin W. Perga, Hoffman Estates, both of Ill.

Universal Oil Products Company, Des Plaines, 111.

Filed: Jan. 19, 1970 Appl. No.: 3,594

Assignee:

..23/288 F, 23/2 E ..F0ln 3/16 ..23/288 F, 2 E; 181/36 C; 60/29, 30

References Cited UNITED STATES PATENTS 3,113,000 12/1963 Gerhold gg /g r3,355,258 11/1967 Thomas ..23/288 F 3,325,256 6/1967 Calvert......23/288 F 3,154,388 10/1964 Purse ..23/288 F Primary ExaminerJosephScovronek Attorney.lames R. Hoatson, Jr. and Philip T. Liggett [5 7]ABSTRACT A catalytic converter-muffler device having a V-shaped bedconfiguration providing optimum gas flow characteristics andminimization of differential expansion problems from hightemperatureconditions. A preferred unit has an oval outer chamber, a catalystreservoir section, and curved sidewalls for the internal catalystretaining screens so as to preclude buckling which occurs with flatplate members.

3 Claims, 5 Drawing Figures PATENTEDHAR 14 I972 3,649,213

FIG. 4

INVENTOR$- Ted 1 DePa/ma Mart/n W Perga ATTORNEYS CATALYTICCONVERTER-MUFFLER The present invention relates to a simplified andimproved form of converter-muffler especially adapted to carry out thecatalytic conversion of automobile exhaust gases.

In particular, the improved unit is designed and constructed in a mannerto have a V-form of catalyst bed in an oval-form chamber and to make useof special catalyst retaining screen members which will divide theinterior of the chamber in a manner to give optimum gas flow andsubstantially eliminate expansion and contraction problems due tohigh-temperature operating conditions.

The desirability of converting the unburned hydrocarbons, CO, nitrogenoxides, etc., from vehicular exhaust gases has been generally publicizedand well established. Also, in order to overcome atmospherecontamination and the problem of smog, it has been widely proposed touse thermal afterburners or various catalytic devices in the exhaust gasflow path to effect as efficient as possible oxidation of the gas streaminto less harmful conversion products. The use of a catalytic system isof advantage in that there is the initiation of the oxidation reactionat a lower temperature than might otherwise be possible and there isalso the elimination of igniting means generally required withafterburners" or other apparatus which depend strictly upon thermalconditions.

One of the problems of catalytic converters has been the expansion andcontraction of internal members so as to cause buckling thereof andbreakage of fabrication connections as well as the squeezing andbreakage of fragile catalyst particles. The breakage and loss ofcatalyst from the retainer section eventually results in a reduction ofoperating efficiency in the converter unit.

It is thus a principal object of the present invention to provide aconverter design and assembly which is adapted to minimize temperatureexpansion problems and preclude a reduced catalytic efficiency fromcatalyst losses in the gas contacting zone.

It is also an object of the present invention to provide an oval orelliptical form of unit and curved sidewalls for the perforated catalystretaining members such that undefined buckling will be precluded as theunit undergoes temperature expansion movements.

In a broad embodiment, the present converter-muffler unit comprises incombination, an elongated tubular form of outer housing having a gasport means at each end thereof, a hollow wed ge-form outer catalystretaining member that is positioned and spaced symmetrically within saidhousing to provide a tapering gas manifold zone therearound in saidhousing that communicates with one of said port means, an innerwedgeform catalyst retaining member spaced from and positioned in firstsaid wedge-form member to provide a resulting V-form catalyst retainingsection therebetween and an inner manifold section, perforations inopposing side portions of each of said members, and a passageway betweensaid inner manifold section of said inner member to the other of saidgas port means, whereby gas flow may pass through said unit andlaterally through said V-form catalyst section in a uniform manner.

In a preferred design and arrangement, the outer shell or housing is ofan oval or elliptical form and the side wall portions for the interiorcatalyst retaining members, which may be of screening or perforate platematerial, will have curvature so as to provide controlled expansion andcontraction under temperature changes and, in turn, eliminateuncontrolled or undefined buckling for such members. Typical flat platepartitioning members must be provided with ribs or other stiffeningmembers in order to preclude in and out warpage or buckling, sometimesreferred to as oil can" effects. On the other hand, a convex or concavemember will generally expand in a controlled and uniform manner and inproportion to the temperature change.

A preferred construction for the improved converter also utilizes twoseparate wedge-form catalyst retaining members which have sidewallperforations. One member is sized to slide inside of the other and leavea space therebetween as a catalyst retaining section. In other words,the unconnected slide fit of one member in the other permitsdifferential expansion to take place without warpage or breakage ofconnections between the two. In still another aspect, there is used anupper and horizontal plate across the top of the inner catalystretaining member that, in turn, is spaced from the top of the outercatalyst retaining member so as to provide for the formation of acatalyst reservoir section. It is, of course, desired that the catalystretaining section should be maintained in a completely filled manner atall times in order to preclude bypassing of catalyst particles by any ofthe gas stream passing through the unit.

With respect to the V-form catalyst retaining section provided in thepresent converter design, it is to be noted that it is of advantage inbeing placed in a straight tubular housing by virtue of providing both atapering gas inlet section and a tapering gas outlet manifold section.Preferably, the gas stream will be introduced into an internal V-shapedinlet section such that there is a decreasing cross-sectional area inthe downstream direction for such inlet section. Thus, as the volume ofgas is decreased due to a stream splitting and the transverse passage ofsuch stream through the opposing portions of the V-formed catalyst bed,there is substantially uniform flow of gas through the length of thecatalyst sections. In a reverse manner, there is an increasingcross-sectional area within outlet manifold section in the downstreamdirection which exists between the outer face of the catalyst bedsection and the inside wall of the tubular form housing so that suchmanifold section readily accommodates the increasing quantity of gasleaving the catalyst bed.

Still further, where desired, the actual thickness of the V- form bedmay be varied from one end to the other so as to provide a quite uniformflow of gas through the entire length of the bed. For example, thedownstream portion of the bed may be made slightly thicker than theupstream portion thereof so that there will be a slightly greaterpressure drop at such downstream end which will tend to balance thehigher static pressure head existing in that area.

Still other advantages and improved features for the special converterdesign will be noted upon reference to the accompanying drawing and thefollowing description thereof.

FIG. 1 of the drawing is a diagrammatic elevational view, partially insection, of the present improved converter muffler unit.

FIG. 2 is a cross-sectional view of the tubular form converter unit, asindicated by the line 2-2 in FIG. 1.

FIG. 3 shows in a plan view, which is partially in section, thearrangement of the V-form catalyst bed within the converter unit.

FIGS. 4 and 5 indicate in a diagrammatic manner the utilization ofseparate wedge-shaped perforate partitioning members as a preferredmeans for providing the catalyst retention in a V-form within theconverter unit.

Referring now particularly to the drawing, there is indicated the use ofan oval or elliptical form tubular housing 1 with a gas inlet port means2 in an end portion 3 and a gas outlet port means 4 in an end section 5.Extending internally from the end of the unit, there is provided ahollow wedge-form catalyst retaining member 6 which, as best shown inFIGS. 2 and 5, has flat nonperforate upper and lower sections connectedby outwardly curved perforate sidewall portions 7. These side portionsmay be made of plate with slots 8 such as shown or of a standardperforated plate stock, as another alternative, the side wall portionsmay be made of wire mesh or screening sized to retain the catalystparticles. In any case the exterior of the outer catalyst retainingmember 6 will be sized to be a slipfit within the oval form housing I,as best indicated in the cross sectional view of FIG. 2.

In addition and in accordance with the present improved design, therewill be an interior catalyst retaining member 9 which is also of ahollow wedge form and is sized to extend from end wall 3 into theinterior of the tapering member 6. The top and bottom portions of member9 are nonperforate while the side wall portions 10 are indicated to beoutwardly curved and perforate in the manner of sidewall portions 7 suchthat there is a resulting catalyst retaining space 1 1 between thespaced apart sidewall sections 7 and 10. Preferably, there will be nodirect attachment between the wall portions of members 6 and 9 in orderthat there may be a slide fit between the two and the accommodation ofany differential expansion that will take place as the converterundergoes operational temperature changes.

With particular reference to FIGS. 2 and 4, it will be noted that thepresent embodiment provides for a partitioning plate 12 to be attachedto the top of inner member 9 and that it has a plurality of spacedopenings 13. Also, the wedge-form member 9 will be sized vertically sothat there is a space 14 between the top of the plate 12 and the topportion of the catalyst retaining catalyst reservoir section. Catalystparticles maintained within the reservoir section should be free toreadily flow down through the openings 13 and into the catalystcontacting section 11 to replace any loss of particles or settlementwhich may occur within this latter section.

The slots or openings 8 within the sidewall portions 7 and of therespective catalyst retaining members 6 and 9 will, as heretofore noted,be sized so as to retain the particular catalyst being used in thecatalyst section 11 of the converter unit. Typically, the catalystparticles will be of spherical form and approximately one-eighth inchesin diameter so that they are free flowing and can readily pass from areservoir section 14 into the main bed section 11 or conversely, suchthat they can be pushed up from the lower bed into the reservoir sectiondue to temperature changes. It is however, not intended to limit the useof the converter of the present invention to any one particular form orsize of particle since they could be in the form of cylinders orpellets, rather than of the spherical form, and may have a nominaldimension of from about onesixteenth inch to about one-fourth inch.Also, mixed sizes of catalyst might well be utilized within the catalystbed section.

Still further, it is not intended to limit the present invention to theuse of any one type of catalyst with respect to chemical makeup orphysical properties. Typically, the catalyst will be of a type adaptedto provide a highefficiency oxidation of the exhaust gas fumes to betreated such that suitable catalysts may well include metals of groupsI, V, VI and VIII of the Periodic Table, particularly copper, chromium,iron, cobalt, nickel, and/or certain of the noble metals such as silver,platinum, palladium, etc. The components may be used singly or incombination with two or more, and generally will be composited with aninorganic refractory oxide such as alumina, silica-alumina,alumina-zirconia, alumina-thoria, alumina-boria, and the like.

With particular reference to FIG. 3 of the drawing, it will be notedthat the arrows show the exhaust gas stream flow to be from port 2 andthe inlet manifold section 15, as provided by the interior of wedge-formmember 9, so that the gas stream is entering a zone of decreasingcross-sectional area and will be split to thus pass through the twoopposing leg portions of the V-form catalyst retaining section 11. As aresult, the contacted gas stream is caused to be collected from theouter faces of walls 7 of the outer member 6 for passage through themanifold section 16 to the outlet port 4. This resulting in-toout flowis of particular operational advantage in that the incoming gas streamfirst contacts the smaller face of the catalyst bed in section 11through the perforate wall means 10 of member 9 and will also have lessinitial shell area so that there are optimum conditions for initiationof catalytic oxidation of the burnable and convertible components of thegas stream. As catalytic oxidation takes place and heat is generated inthe inlet face of the V-form bed 11, the heat will then progressdownstream through the bed to provide for a high-efficiency catalyticoxidation. It will be noted when viewing FIG. 3, that gas flow mightwell be from port means 4 through manifold means 16 into the outerretaining member 6 and thence outwardly from the inner member 9 tomanifold zone and to port means 2. However, with this reverse flow,there is the initial contacting of a large surface area of catalystalong outer member 6 and the necessary heating of this larger area toinitiate catalytic oxidation, so that a slower and less efficientconversion exhaust gas fumes will take place upon the starting of anauto engine.

Although FIG. 3 of the drawing indicates the opposing legs 11 of theV-form catalyst bed to be of substantial uniform width throughout theirlength, it is to be noted, as hereinbefore briefly set forth, that thewidth of the catalyst bed may be increased in the downstream directionso that there is a slightly greater pressure drop through such areas anda resulting greater uniformity of gas flow, and uniformity of spacevelocity, with respect to the continuous gas flow through the entirecatalyst section.

Generally, it has been found that catalyst containing converter units ofthe present type have provided satisfactory muffling of sound withrespect to exhaust gas flow from an automobile engine. However, wheredesired, suitable additional resonator or muffler means may be providedas an end portion of the tubular housing 1 or may be added downstreamfrom outlet port means 4 of the converter section. It has alsoheretofore been noted that the outer housing or chamber 1 should be ofan elliptical or oval form in order to provide a flattened convenientshape for the installation of the com verter; however, it is obviousthat the present tubular form converter could be of a substantiallycylindrical form, or in a polygonal form, and still accommodate theinner catalyst retaining members which are of the wedge-shape so as toprovide the resulting V-form catalyst bed within the unit together withthe accompanying advantages for such type of design and arrangement.

A removable catalyst fill-plug 17 has been shown diagrammatically asbeing in the end plate 3, as best shown in FIG. 3, so that catalyst maybe readily introduced into the catalyst retaining section 11 as well asinto the catalyst reservoir section 14; however, the type of fill-plugand the positioning thereof are merely diagrammatic and it is notintended to limit the improved type of converter design and arrangementto any one type of fill-plug means or to a particular positioning in thehousing with respect to the catalyst retaining sections.

What we claim is:

l. A catalytic converter-muffler apparatus for treating an exhaust gasstream, which comprises in combination, an elongated tubular form ofouter housing having a gas inlet port means at one end thereof and a gasoutlet port means at the opposing end thereof, a hollow wedge-form outercatalyst retaining member having outwardly curving perforated sidewallportions and that is positioned and spaced symmetrically within saidhousing to provide a tapering gas manifold zone therearound in saidhousing that communicates with said outlet port means, an inner hollowwedge-form catalyst retain ing member of less length and width than saidouter member also having outwardly curving perforated sidewall portionsthat are spaced from and positioned in first said wedge-form member toprovide a resulting curved wall catalyst retaining section with twoconverging and connecting leg portions in a V-form manner and an innerwedge-form gas inlet manifold section, and a passageway between saidinner manifold section and said gas inlet port means, whereby gas flowmay pass into said apparatus and split laterally through said legportions of the V-form catalyst section in a manner providing gas streamintroduction through an inlet face of the latter that has lesser areathan the outlet face of such section.

2. The apparatus of claim 1 further characterized in that the innerwedge-form catalyst retaining member is of less height than first saidouter catalyst retaining member and that a partitioning plate acrosssaid inner member with perforations therethrough and having a width tofit into said outer member defines thereabove a catalyst reservoir spacecommunicating with the V-form catalyst retaining section between theinner and outer wedge-form members.

3. The converter apparatus of claim 1 further characterized in that bothof said wedge-form catalyst retaining members have nonperforate top andbottom portions and said inner catalyst retaining member is sized to bea slip-fit into first said outer catalyst retaining member, and thelatter is sized to be a slip-fit into said tubular form housing.

2. The apparatus of claim 1 further characterized in that the innerwedge-form catalyst retaining member is of less height than first saidouter catalyst retaining member and that a partitioning plate acrosssaid inner member with perforations therethrough and having a width tofit into said outer member defines thereabove a catalyst reservoir spacecommunicating with the V-form catalyst retaining section between theinner and outer wedge-form members.
 3. The converter apparatus of claim1 further characterized in that both of said wedge-form catalystretaining members have nonperforate top and bottom portions and saidinner catalyst retaining member is sized to be a slip-fit into firstsaid outer catalyst retaining member, and the latter is sized to be aslip-fit into said tubular form housing.